Definetly more power. The car feels like a different car to me. It accelerates faster with less lag. The non catted is rated about 3 hp more but I wanted to stay green with the catted version. Taking the old one out took some time. I found heating the oxygen sensors with a mini torch & the same with the bolts connecting the cat to the exhaust was the best way to break them free. Just keep the torch on the metal part of the sensor & stay away from the wire. Once you have the old one out putting the new one in is easy. It took me about 4 hours total. Money well spent !